Conventionally, ABS resin or PC/ABS resin is mainly used as a thermoplastic resin suited to plating from the aspect of being excellent moldability, impact resistance and the like. And, a plated resin product obtained by applying direct plating method excellent in safety, workability and the like to a molded article composed of these resins or resin compositions, and a resin composition suitable for such a molded article have been investigated (cf. JP-A 2002-338636, JP-A 2003-327817).
A main method for plating onto a resin molded article is one including attaching a catalyst on a surface of the molded article, treating the surface with a dilute acid solution, being subject to electroless copper plating or electroless nickel plating to form a conductive layer, and forming a metal film or an alloy film on it by electroplating.
However, formaldehyde which is used as a reducing agent, being toxic is widely formulated in a solution for electroless copper plating and health problem to workers is indicated. Additionally, since this solution sometimes contain a complexing agent such as EDTA which is strongly functioning in order to make copper ion solubilize in an alkali solution, too much labor for eliminating metal ions in drainage treatment (a process including filtration->treatment with activated carbon->ion exchanging and the like is necessary) is required, causing many problems.
Further, a solution for electroless nickel plating contains a phosphinate as a reducing agent, and when the solution is used, this phosphinate may be oxidized to generate a phosphite that is in controlled substances, being problem. In addition, this drainage after plating is a high COD solution and is presently an environmental pollutant.
Considering occupational health and safety and global environment, direct plating method including no electroless plating step as a method for plating onto a resin molded article is proposed and practical application is studied. Specific example of direct plating includes a Pd—Sn colloid catalystic method that is disclosed in JP-A H7-11487, JP-A H11-61425 and the like.